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2 produkter
2 produkter
E-bok
Engelska, 20092 589 kr
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Biology is a very popular subject among the students. Many students take a keen interest in Biology as it is considered as a foundation stone in a Medical Career. Study of Plants, Animals, Dissection of Animals, Study of Tissue, Life Cycles and Classification of Plants and Animals all one important for students. This Encyclopaedia distresses the various aspects of Biological Science. It has been prepared for all Medical students keeping in mind their needs and requirements. Today biological science is rising on a wall of worry. No other science has advanced more dramatically during the past several decades nor yielded so many palpable improvements in human welfare. Thus it is aimed at a broad range of readers. This book differs from the other books in its central concern with "statement about the future" as made by a wide range of scientists. The subject areas covered are extensive and specialists in every field will find materials than can be improved and extended. This encyclopaedia is an effort to summarize the basic concept and principles of the subject, to present the elementary factual information with which a person to be competent in the filed should be familiar, and to sow how these principles and facts may be applied in a practical way to the interests and welfare of Students."
E-bok
Engelska, 201111 866 kr
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Biodilution is also a process that occurs to all trophic levels in an aquatic environment; it is the opposite of biomagnification, thus a pollutant gets smaller in concentration as it progresses up a food web. Lipid, (lipophilic) or fat soluble substances cannot be diluted, broken down, or excreted in urine, a water-based medium, and so accumulate in fatty tissues of an organism if the organism lacks enzymes to degrade them. When eaten by another organism, fats are absorbed in the gut, carrying the substance, which then accumulates in the fats of the predator. Since at each level of the food chain there is a lot of energy loss, a predator must consume many prey, including all of their lipophilic substances. In a review of a large number of studies, Suedeletal. (1994) concluded that although biomagnification is probably more limited in occurrence than previously thought, there is good evidence that DDT, DDE, PCBs, toxaphene, and the organic forms of mercury and arsenic do biomagnify in nature. For other contaminants, bioconcentration and bioaccumulation account for their high concentrations in organism tissues. More recently, Gray (2002) reached a similar substances remaining in the organisms and not being diluted to non-threatening concentrations. The success of top predatory-bird recovery (bald eagles, peregrine falcons) in North America following the ban on DDT use in agriculture is testament to the importance of biomagnification. The present publication has been designed to approach this subject in a simple and lucid style. The method of presentation is very clear and lucid, which can be easily followed by the students.